Import ruby/yarp from a release branch

Author: andrykonchin

src/main/c/yarp/include/yarp/ast.h

@@ -654,7 +654,7 @@ typedef struct yp_constant_path_operator_write_node {
 // ConstantPathWriteNode
 typedef struct yp_constant_path_write_node {
     yp_node_t base;
-    struct yp_node *target;
+    struct yp_constant_path_node *target;
     yp_location_t operator_loc;
     struct yp_node *value;
 } yp_constant_path_write_node_t;

src/main/c/yarp/include/yarp/version.h

@@ -1,5 +1,5 @@
 #define YP_VERSION_MAJOR 0
-#define YP_VERSION_MINOR 4
+#define YP_VERSION_MINOR 6
 #define YP_VERSION_PATCH 0
 
-#define YP_VERSION "0.4.0"
+#define YP_VERSION "0.6.0"